This invention relates to an apparatus for detecting defects on the sidewalls of bottles.
It is necessary to inspect glass bottles containing liquors, beverages, foods, etc. for any defects whether they are newly made or have been recovered for reuses. The bottles are inspected on parts thereof, i.e., the bodies or sidewalls, bottoms, tops of the mouths and threaded bottle necks. Among these parts, the sidewalls tend to have defects, such as foreign matters or smears which may cause sanitary problems, and cracks, scraches, seeds, blisters, etc. which may cause bottle breakages. It is necessary to inspect the bottles accurately for any of these defects.
Generally the apparatus for detecting defects on bottle sidewalls utilizes the fact that a portion of a defect appears darker than the other portion, in inspecting the sidewalls for defects. This apparatus has found it easy to detect defects, such as opaque foreign matters, etc. which are very light blocking, but has found it difficult to detect accurately defects, such as light smears, streaks, blisters, etc. which are opaque and are extended over large areas. That is, a problem with this generally used apparatus is that when the sensitivity of a photoelectric device is increased to detect these opaque large defects, even noises due to different colors, different thicknesses of the sidewalls, etc. are detected as defects.